Configuring the MTU for a Serial Interface
This section describes how to configure the maximum transmission unit (MTU) for a serial interface. The MTUs for two directly connected serial interfaces must be the same. Otherwise, the link between the two interfaces cannot transmit services.
Context
Ensure that the MTU for an interface is the same as that for its directly connected interface. Otherwise, services may be interrupted.
The length of a quality of service (QoS) queue is limited. If the MTU is too small, a packet may be divided into many fragments. If the number of fragments exceeds the length of a QoS queue, the QoS queue drops fragments. To avoid this situation, increase the MTU. By default, a serial interface uses the first in first out (FIFO) queue scheduling mechanism.
Procedure
- Run system-view
The system view is displayed.
- Run interface serial interface-number
The serial interface view is displayed.
- Run link-protocol ppp
The link layer protocol is configured as PPP for the serial interface.
- Run mtu
The MTU is configured for the serial interface.
Generally, it is recommended that you use the default MTU value of 1500 bytes.
- Run commit
The configuration is committed.
